Tracer-containing compositions

ABSTRACT

The present invention relates to the field of compression refrigeration and air conditioning. Specifically, the present invention relates to a tracer-containing compositions comprising refrigeration/heating fluid and tracer compound(s). Additionally, the present invention relates to a method for detecting tracer compounds to identify gases after leaving the custody of the original manufacturer or prior source, and the verification of authenticity. The aforementioned method provides for the detection of tracer compounds, which in turn, may alert the refrigeration industry to when dilution, adulteration, contamination or other unauthorized practices have occurred with refrigeration products.

CROSS REFERENCE(S) TO RELATED APPLICATION(S)

This application claims the priority benefit of U.S. Provisional PatentApplication 60/548,085, filed Feb. 26, 2004, which is herebyincorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to the field of compression refrigerationand air conditioning. Specifically, the present invention relates to acomposition comprising refrigerant and tracer compound(s). Additionally,the present invention relates to a method for the identification ofrefrigerant gases after leaving the custody of the original manufacturerand the verification of refrigerant authenticity. The aforementionedmethod provides for the detection of tracer compounds, which in turn,may alert the refrigeration industry to the occurrence of dilution,adulteration, contamination or other unauthorized modification ofrefrigeration products.

2. Description of Related Art

Environmental concerns have led the refrigeration industry to highlevels of consciousness around the responsible use of refrigerants. Therefrigeration industry, as well as the society at large, benefits wheneveryone who manufactures, distributes, uses refrigerants, or servicesrefrigeration and air conditioning equipment uses all applicablemeasures to keep equipment operating at the highest achievable level ofenergy efficiency. This reduces the amount of energy consumed by theequipment. Higher than necessary energy consumption, as well as leakageof refrigerants, can contribute to unnecessary pollution of ouratmosphere and waste of existing resources. This unnecessary waste alsocomes at a cost to the consumer for replacement of leaked refrigerant.

In response to environmental concerns, manufacturers of refrigerantshave developed new refrigerant products that allow higher levels ofenergy efficiency when used in properly designed equipment. The newgeneration HFC refrigerants have less impact on the environment thanolder generation chlorinated refrigerants in the event that theyinadvertently leak into the atmosphere. The HFC refrigerants have zeroozone depletion potential, and in general have less tropospheric climatechange potential than the refrigerants they replace. In addition,industry practices now mandate the elimination of leaks from most typesof operating equipment, and require that refrigerant gas be recoveredfrom equipment when that equipment is taken out of service or is openedto allow service work to be performed.

While the new high efficiency refrigerants and new responsible usepolicies are benefiting the environment, the benefit is not as great asit could be. In some instances, the recovered refrigerant gases are notproperly reclaimed or recycled. The recovered refrigerant may bere-installed back into other pieces of equipment without being properlyreclaimed and cleaned to remove any harmful or energy efficiencyreducing impurities which may have been introduced in handling or as aresult of poorly performing or damaged equipment. The equipment intowhich this refrigerant is introduced will then not operate at peakefficiency, and will consume more energy than necessary.

In addition, used refrigerant can be blended with virgin refrigerant,which generally results in a non-standard refrigerant gas composition.

Similarly, used refrigerant can be re-packaged and sold as virginrefrigerant, without certification of purity and quality. Thesepractices may result in increased atmospheric pollution and increasedenergy use, and places expensive refrigeration hardware at risk of beingdamaged.

In addition to negative environmental and equipment impact, there areeconomic losses to the refrigerant manufacturers and distributors.Refrigerant manufacturers make significant investments into thedevelopment of the quality new refrigerants products. Refrigerantdistributors similarly have invested in equipment for the properprotection of refrigerants from contamination during packaging, storage,and distribution of refrigerants When refrigerants are diluted orblended with recovered refrigerants, and sold as virgin refrigerant,manufacturers and distributors do not receive the benefit of theirinvestment.

For the foregoing reasons, there has been a need for the ability topositively determine when a refrigerant composition is diluted oraltered in any way, in a manner that does not compromise performance orthe product properties to any measurable extent.

The present invention addresses this need by providing a highly secureway to label virgin refrigerant product.

BRIEF SUMMARY OF THE INVENTION

The present invention is directed to a tracer-containing refrigerantcomposition, said composition comprising a refrigeration/heating fluidand at least one tracer compound, said tracer compound being present andanalytically detectable and being selected from the group consisting ofhydrofluorocarbons, deuterated hydrofluorocarbons, perfluorocarbons,fluoroethers, brominated compounds, iodated compounds, alcohols,aldehydes and ketones, nitrous oxide and combinations thereof.Additionally, the present invention relates to a composition as statedabove wherein at least one of said tracer compound is present as asingle pre-determined isomer.

The present invention further relates to a method of using the presentinventive tracer-containing refrigerant compositions, said methodcomprising combining said tracer compound with saidrefrigeration/heating fluid to make a tracer-containing refrigerantcomposition, and detecting the presence of said tracer compound in saidtracer-containing refrigerant composition. Said method may comprisedetecting the occurrence of dilution, adulteration or contamination ofsaid composition.

Also, the present invention relates to use of the tracer-containingrefrigerant composition in a method for producing refrigerationcomprising evaporating said composition in the vicinity of a body to becooled and thereafter condensing said composition. And the presentinvention additionally relates to a method of using thetracer-containing refrigerant composition for producing heat comprisingcondensing said composition in the vicinity of a body to be heated andthereafter evaporating said composition.

DETAILED DESCRIPTION OF THE INVENTION

Applicants specifically incorporate the entire contents of all citedreferences in this disclosure. Further, when an amount, concentration,or other value or parameter is given as either a range, preferred range,or a list of upper preferable values and lower preferable values, thisis to be understood as specifically disclosing all ranges formed fromany pair of upper range limit or preferred value and any lower rangelimit r preferred value, regardless of whether such ranges areseparately disclosed. Where a range of numerical values is recitedherein, unless otherwise stated, the range is intended to include theendpoints thereof, and all integers and fractions within the range. Itis not intended that the scope of the present invention be limited tothe specific values recited when defining a range.

The refrigeration/heating fluid of the present invention may be anycommon refrigeration/heating fluid used in the refrigeration industry.Such refrigeration/heating fluids may be hydrofluorocarbons (HFCs),hydrochlorofluorocarbons (HCFCs), perfluorocarbons (PFCs), fluorocarbonethers (HFEs), hydrocarbons, carbon dioxide (CO₂), ammonia (NH₃), ormixtures thereof. The fluorinated refrigeration/heating fluids, HFCs,HCFCs, HFEs and PFCs may be referred to as fluorocarbon refrigerants.

The fluorocarbon refrigerants of the present invention may have 1-8carbon atoms, contain at least one fluorine atom, optionally containchlorine and oxygen atoms, and have a normal boiling point of from −90°C. to 80° C. These fluorocarbons may be represented by the generalformula C_(w)F_(2w+2−x−y)H_(x)Cl_(y)O_(z), wherein w is 1-6, x is 0-9, yis 0-3, and z is 0-2, and wherein 2w+2−x−y is a positive integer.

Preferred of the fluorocarbons are those in which w is 1-6, x is 1-5, yis 0-1, and z is 0-1. The present invention is particularly useful withhydrofluorocarbon and hydrochlorofluorocarbon-based refrigerants.Fluorocarbon refrigerants are commercial products available from anumber of sources such as E. I. du Pont de Nemours & Co.,Fluoroproducts, Wilmington, Del., 19898, USA, or are available fromcustom chemical synthesis companies such as PCR Inc., P.O. Box 1466,Gainesville, Fla., 32602, USA, and additionally by synthetic processesdisclosed in publications such as Chemistry of Organic FluorineCompounds 2^(nd) (revised edition), edited by Milos Hudlicky, publishedby Ellis Harwood-Prentice Hall Publishers, 1992. Representativefluorocarbons include but are not limited to: CHClF₂ (HCFC-22), CHF₃(HFC-23), CH₂F₂ (HFC-32), CH₃F (HFC-41), CF₃CF₃(FC-116), CHClFCF₃(HCFC-124), CHF₂CF₃ (HFC-125), CH₂ClCF₃ (HCFC-133a), CHF₂CHF₂ (HFC-134),CH₂FCF₃ (HFC-134a), CClF₂CH₃ (HCFC-142b), CHF₂CH₂F (HFC-143), CF₃CH₃(HFC-143a), CHF₂CH₃ (HFC-152a), CHF₂CF₂CF₃ (HFC-227ca), CF₃CFHCF₃(HFC-227ea), CHF₂CF₂CHF₂ (HFC-236ca), CH₂FCF₂CF₃ (HFC-236cb), CHF₂CHFCF₃(HFC-236ea), CF₃CH₂CF₃ (HFC-236fa), CH₂FCF₂CHF₂ (HFC-245ca), CH₃CF₂CF₃(HFC-245cb), CHF₂CHFCHF₂ (HFC-245ea), CH₂FCHFCF₃ (HFC-245eb), CHF₂CH₂CF₃(HFC-245fa), CH₂FCF₂CH₂F (HFC-254ca), CH₃CF₂CHF₂ (HFC-254cb),CH₂FCHFCHF₂ (HFC-254ea), CH₃CHFCF₃ (HFC-254eb), CHF₂CH₂CHF₂ (HFC-254fa),CH₂FCH₂CF₃ (HFC-254fb), CH₃CF₂CH₃ (HFC-272ca), CH₃CHFCH₂F (HFC-272ea),CH₂FCH₂CH₂F (HFC-272fa), CH₃CH₂CF₂H (HFC-272fb), CH₃CHFCH₃ (HFC-281ea),CH₃CH₂CH₂F (HFC-281fa), CHF₂CF₂CF₂CF₂H(HFC-338 pcc), CF₃CH₂CF₂CH₃(HFC-365mfc), CF₃CF₂CF₂OCHFCF₃ (Freon® E1), CF₃CHFCHFCF₂CF₃(HFC-43-10mee), C₄F₉OCH₃, and C₄F₉OC₂H₅.

Additionally, the fluorocarbon refrigerants of the present invention maybe represented by the general formula C_(w)F_(2w−x)H_(x)O_(z), wherein wmay equal 3 to 8 and x may equal 0-17 and z may equal 0 to 2, andwherein 2w−x is a positive integer. Such fluorocarbon refrigerantsinclude unsaturated compounds and other functionalized fluorocarbons,such as CF₃(CF₂)₃CH═CH₂ (perfluorobutylethylene, PFBE),CF₃CF₂C(O)CF(CF₃)₂(perfluoroethylisopropylketone, PEIK), andCF₃C(O)CF(CF₃)₂(perfluoromethylisopropylketone, PMIK).

More preferred fluorocarbon refrigerants are the hydrofluorocarbon andhydrochlorofluorocarbon-based refrigerants, such as, CHClF₂ (HCFC-22),CHF₃ (HFC-23), CH₂F₂ (HFC-32), CHClFCF₃ (HCFC-124), CHF₂CF₃ (HFC-125),CHF₂CHF₂ (HFC-134), CH₂FCF₃ (HFC-134a), CF₃CH₃ (HFC-143a), CHF₂CH₃(HFC-152a), CHF₂CF₂CF₃ (HFC-227ca), CF₃CFHCF₃ (HFC-227ea), CF₃CH₂CF₃(HFC-236fa), CHF₂CH₂CF₃ (HFC-245fa), CHF₂CF₂CF₂CF₂H(HFC-338 pcc),CF₃CHFCHFCF₂CF₃ (HFC-43-10mee), CF₃(CF₂)₃CH═CH₂ (perfluorobutylethylene,PFBE), CF₃CF₂C(O)CF(CF₃)₂ (perfluoroethylisopropylketone, PEIK),CF₃C(O)CF(CF₃)₂ (perfluoromethylisopropylketone, PMIK); and theazeotropic and azeotrope-like fluorocarbon refrigerant compositions,such as, HCFC-22/HFC-152a/HCFC-124 (known by the ASHRAE designations,R-401A, R-401B, and R-4010), HFC-125/HFC-143a/HFC-134a (known by theASHRAE designation, R-404A), HFC-32/HFC-125/HFC-134a (known by ASHRAEdesignations, R-407A, R-407B, and R-4070), HCFC-22/HFC-143a/HFC-125(known by the ASHRAE designation, R-408A), HCFC-22/HCFC-124/HCFC-142b(known by the ASHRAE designation: R-409A), HFC-32/HFC-125 (R-410A), andHFC-125/HFC-143a (known by the ASHRAE designation: R-507).

The fluorocarbon refrigerants of the present invention may optionallyfurther comprise up to 10 weight percent of dimethyl ether, or at leastone C₃ to C₅ hydrocarbon, e.g., propane, propylene, cyclopropane,n-butane, isobutane, n-pentane, cyclopentane and neopentane(2,2-dimethylpropane). Examples of fluorocarbons containing such C₃ toC₅ hydrocarbons are azeotrope-like compositions ofHCFC-22/HFC-125/propane (known by the ASHRAE designation, R-402A andR-402B), HCFC-22/octafluoropropane/propane (known by the ASHRAEdesignation, R-403A and R-403B), octafluoropropane/HFC-134a/isobutane(known by the ASHRAE designation, R-413A),HCFC-22/HCFC-124/HCFC-142b/isobutane (known by the ASHRAE designation,R-414A and R-414B), HFC-134a/HCFC-124/n-butane (known by the ASHRAEdesignation, R-416A), HFC-125/HFC-134a/n-butane (known by the ASHRAEdesignation, R-417A), HFC-125/HFC-134a/dimethyl ether (known by theASHRAE designation, R-419A), and HFC-125/HFC-134a/isobutane (known byASHRAE designation, R-422A).

The tracer compound of the present invention is selected from the groupconsisting of hydrofluorocarbon, deuterated hydrocarbon orhydrofluorocarbon, perfluorocarbon, fluoroether, brominated compound,iodated compound, alcohol, aldehydes and ketone, nitrous oxide (N₂O) andcombinations thereof. While there may be overlap between a definedchemical compound, which may be a refrigeration/heating fluid, and achemical compound that may be defined as a tracer compound, the samecompound may not serve as both elements of a given composition. Suitabletracer compound candidates are listed in Table 1.

TABLE 1 CAS registry Compound Name Chemical Structure no. Deuteratedhydrocarbon or HFC compounds Ethane-d6 CD₃—CD₃ 1632-99-1 Propane-d8CD₃—CD₂—CD₃ 2875-94-7 HFC-32-d2 CD₂F₂ 594-24-1 HFC-134a-d2 CD₂F—CF₃496024-52-3 HFC-143a-d3 CD₃—CF₃ 558-59-8 HFC-125-d CDF₂—CF₃ 87458-21-7HFC-227ea-d CF₃—CDF—CF₃ 119117-94-1 HFC-227ca-d CF₃—CF₂—CDF₂ 662-02-2HFC-134-d2 CDF₂—CDF₂ 274689-13-3 HFC-236fa-d2 CF₃—CD₂—CF₃ 72256-43-0HFC-245cb-d3 CF₃—CF₂—CD₃ 38878-30-7 HFC-263fb-d2* CF₃—CD₂—CH₃ 7370-99-2HFC-263fb-d3 CF₂—CH₂—CD₃ 7371-43-9 Fluoroethers HFOC-125E CHF₂—O—CF₃3822-68-2 HFOC-134aE CH₂F—O—CF₃ 2261-01-0 HFOC-143aE CH₃—O—CF₃ 421-14-7HFOC-227eaE CF₃—O—CHF—CF₃ 2356-62-9 HFOC-236faE CF₃—O—CH₂—CF₃ 20193-67-3HFOC-245faEβγ or CHF₂—O—CH₂CF₃ 1885-48-9 HFOC-245faEαβ (orCHF₂CH₂—O—CF₃) (or 84011-15-4) HFOC-245cbEβγ or CH₃—O—CF₂—CF₃ 22410-44-2HFOC-245cbαβ (or CH₃—CF₂—O—CF₃) (or HFE-42-11mcc (or Freon ®CF₃—CF₂—CF₂—O—CHF—CF₃ 3330-15-2 E1) Freon ® E2CF₃—CF₂—CF₂—O—CF(CF3)CF₂—O—CHF—CF₃ 3330-14-1 Hydrofluorocarbons HFC-23CHF₃ 75-46-7 HFC-161 CH₃—CH₂F 353-36-3 HFC-152a CH₃—CHF₂ 75-37-6 HFC-134CHF₂—CHF₂ 359-35-3 HFC-227ea CF₃—CHF—CF₃ 431-89-0 HFC-227ca CHF₂—CF₂—CF₃2252-84-8 HFC-236cb CH₂F—CF₂—CF₃ 677-56-5 HFC-236ea CF₃—CHF—CHF₂431-63-0 HFC-236fa CF₃—CH₂—CF₃ 690-39-1 HFC-245cb CF₃—CF₂—CH₃ 1814-88-6HFC-245fa CHF₂—CH₂—CF₃ 460-73-1 HFC-254cb CHF₂—CF₂—CH₃ 40723-63-5HFC-254eb CF₃—CHF—CH₃ 421-48-7 HFC-263fb CF₃—CH₂—CH₃ 421-07-8 HFC-272caCH₃—CF₂—CH₃ 420-45-1 HFC-281ea CH₃—CHF—CH₃ 420-26-8 HFC-281faCH₂F—CH₂—CH₃ 460-13-9 HFC-329p CHF₂—CF₂CF₂CF₃ 375-17-7 HFC-329mmz(CH₃)₂—CH—CF₃ 382-24-1 HFC-338mf CF₃—CH₂—CF₂—CF₃ 2924-29-0 HFC-338pccCHF₂—CF₂—CF₂—CHF₂ 377-36-6 HFC-347s CH₃—CF₂—CF₂—CF₃ 662-00-0HFC-43-10mee CF₃—CHF—CHF—CF₂—CF₃ 138495-42-8 Perfluorocarbons PFC-116CF₃—CF₃ 76-16-4 PFC-C216 Cyclo(—CF₂—CF₂—CF₂—) 931-91-9 PFC-218 CF₃CF₂CF₃76-19-7 PFC-C318 Cyclo(—CF₂—CF₂—CF₂—CF₂—) 115-25-3 PFC-31-10mcCF₃—CF₂—CF₂—CF₃ 355-25-9 PFC-31-10my (CF₂)₂CF—CF₃ 354-92-7PEC-C51-12mycm Cyclo(—CF(CF₃)—CF₂—CF(CF₃)—CF₂—) 2994-71-0 PEC-C51-12mym,trans Cyclo(—CF₂—CF(CF₃)—CF(CF₃)—CF₂—) 1583-98-8 PEC-C51-12mym, cisCyclo(—CF₂—CF(CF₃)—CF(CF₃)—CF₂—) 1583-97-7 Perfluoromethylcyclo-Cyclo(—CF₂—CF₂(CF₃) —CF₂—CF₂—CF₂—) 1805-22-7 pentanePerfluoromethylcyclo- Cyclo(CF₂—CF₂(CF₃)—CF₂—CF₂—CF₂—CF₂—) 355-02-2hexane Perfluorodimethylcyclo- Cyclo(—CF₂—CF₂(CF₃)—CF₂—CF₂(CF₃)—CF₂—)ortho-306-89-9 hexane (ortho, meta, or meta-335-27-3 para) para-374-77-6Perfluoroethylcyclohexane Cyclo(—CF₂—CF₂(CF₂CF₃)—CF₂—CF₂—CF₂—CF₂—)335-21-7 Perfluoroindan C₉F₁₀ (see structure below) 1736-47-6

Perfluorotrimethylcyclo- Cyclo(—CF₂(CF₃)—CF₂(CF₃)—CF₂—CF₂(CF₃)—CF₂—)374-76-5 hexane (all possible isomers) Perfluoroisopropylcyclo-Cyclo(—CF₂CF₂(CF₂(CF₃)₂)CF₂CF₂CF₂CF₂—) 423-02-9 hexane Perfluorodecalin(cis or trans, trans shown) C₁₀F₁₈ (see structure below)

306-94-5 Perfluoromethyldecalin (cis or trans and all additionalpossible isomers) C₁₁F₂₀ (see structure below)

306-92-3 Brominated Compounds Bromomethane CH₃Br 74-83-9Bromofluoromethane CH₂FBr 373-52-4 Bromodifluoromethane CHF₂Br 1511-62-2Dibromofluoromethane CHFBr₂ 1868-53-7 Tribromomethane CHBr₃ 75-25-2Bromoethane CH₃—CH₂Br 74-96-4 Bromoethene CH₂═CHBr 593-60-21,2-dibromoethane CH₂Br—CH₂Br 106-93-4 1-bromo-1,2- CFBr═CHF 358-99-6difluoroethene Iodated compounds Iodotrifluoromethane CF₃I 2314-97-8Difluoroiodomethane CHF₂I 1493-03-4 Fluoroiodomethane CH₂FI 373-53-51,1,2-trifluoro-1- CF₂I—CH₂F 20705-05-9 iodoethane1,1,2,2-tetrafluoro-1- CF₂I—CHF₂ 354-41-6 iodoethane1,1,2,2-tetrafluoro-1,2- CF₂I—CF₂I 354-65-4 diiodoethaneIodopentafluorobenzene C₆F₅I 827-15-6 Alcohols Ethanol CH₃—CH₂—OH64-17-5 n-propanol CH₃—CH₂—CH₂—OH 71-23-8 Isopropanol CH₃—CH(OH)—CH₃67-63-0 Aldehydes and Ketones Acetone (2-propanone) CH₃—CO—CH₃ 67-64-1n-propanal CH₃—CH₂—CHO 123-38-6 n-butanal CH₃—CH₂—CH₂—CHO 123-72-8Methyl ethyl ketone (2- CH₃—CO—CH₂—CH₃ 78-93-3 butanone) Other Nitrousoxide N₂O 10024-97-2

The compounds listed in Table 1 are available commercially (fromchemical supply houses, such as Aldrich, Milwaukee, Wis.) or may beprepared by processes known in the art.

Single tracer compounds may be used in combination with arefrigeration/heating fluid in the compositions of the present inventionor multiple tracer compounds may be combined in any proportion to serveas a tracer blend. The tracer blend may contain multiple tracercompounds from the same class of compounds or multiple tracer compoundsfrom different classes of compounds. For example, a tracer blend maycontain 2 or more deuterated hydrofluorocarbons, or one deuteratedhydrofluorocarbon in combination with one or more perfluorocarbons.

Additionally, some of the compounds in Table 1 exist as multipleisomers, structural or optical. Single isomers or multiple isomers ofthe same compound may be used in any proportion to prepare the tracercompound. Further, single or multiple isomers of a given compound may becombined in any proportion with any number of other compounds to serveas a tracer blend.

The tracer-containing refrigerant compositions of the present inventionmay be prepared by any convenient method to combine the desired amountof the individual components. A preferred method is to weigh the desiredcomponent amounts and thereafter combine the components in anappropriate vessel. Agitation may be used, if desired.

By “analytically detectable” is meant that the tracer or tracer blendmay be detected by any analytical method capable of differentiating thetracer from the refrigeration/heating fluid or capable of determiningthe quantity of tracer present. In the case where a dilution of thetracer-containing composition may have occurred, the tracer compound maybe present in a lesser quantity than originally added to therefrigeration/heating fluid. Analytical detection of the lesser quantitywould aid the refrigeration industry. Such detection is capable ofalerting the industry to the occurrence of dilution, adulteration, orcontamination. Additionally, manufacturers, distributors and purchaserswould be able to verify or authenticate the source (ie., supplier) ofthe refrigerant composition by comparing any quantity of detected tracerto the quantity that was intentionally combined withrefrigeration/heating fluid by the source.

Gas chromatography (GC) is one analytical method that may be used todetect and quantify the tracer or tracer blend in therefrigeration/heating fluid. Any GC detector may be used that is capableof detecting and quantifying the tracer compound. Such detectorsinclude, but are not limited, to flame ionization detector (FID),thermal conductivity detector (TCD), electron-capture detector (ECD),photo-ionization detector (PID), infrared detectors (IRD) and massspectrometer detectors (usually referred to as GC-MS when combined witha gas chromatograph). Other analytical methods may be utilized which donot require the gas chromatographic separation prior to detection. Suchadditional analytical methods include but are not limited to nuclearmagnetic resonance (NMR) or infrared (IR) spectrometry.

When mixtures of this invention are analyzed using gas chromatography,conditions capable of identifying and quantifying the tracer in thepresence of the refrigeration/heating fluid may be used. The GC columnused for the analysis must be chosen so as to be capable of separatingthe tracer compound or components of the tracer blend from therefrigeration/heating fluid. Both packed and capillary GC columns may beused. The preferred GC columns are those known to provide separation offluorocarbon compounds from each other and classes of candidate tracercompounds of the present invention.

The packed GC columns that may be useful in the present invention arefrom about 1 meter to about 12 meters in length. Generally, packed GCcolumns are constructed of stainless steel. The commercially availablepacked GC columns that may be useful in the present invention includebut are not limited to: porous polymer stationary phase, such asPorapak® Q or Porapak® T; silicone polymer stationary phases, such asSP®-1000 on Carbopack® B support or SP®-2100 (methyl silicone) onSupelcoport® support, perfluorinated polymer stationary phase, Fluorcol®on Carbopack® B support; and polyethylene glycol stationary phases, suchas Carbowax® on Carbopack® C support. For those packed GC columns thatare packed with a polymer coated support, the polymer loading may rangefrom about 0.1% to about 10%. Packed GC columns listed here areavailable from Supelco (Bellefonte, Pa.).

Capillary GC columns which are found useful in the present invention areavailable commercially. Capillary columns may vary in length from about10 meters to about 105 meters, but may also be longer if two or morecolumns are joined together (e.g. 120 meters by joining two 60 metercapillary GC columns). The capillary GC columns that may be of use inthe present invention are generally constructed of fused silica tubingand vary in inner diameter (ID) from about 0.1 millimeter to about 0.53millimeter. The stationary phase for the capillary GC columns is coatedon the interior surface of the column and may vary in thickness fromabout 0.1 micrometer to about 5 micrometers. The stationary phases thatmay be of use in the present invention, include but are not limited tothe commercially available liquid polymer phases: RT_(x)®-1 ((Crossbond®100% dimethyl polysiloxane), RT_(x)®-200 (Crossbond®trifluoropropylmethyl polysiloxane), RT_(x)®-1301 (Crossbond® 6%cyanopropylphenyl/94% dimethyl polysiloxane), RT_(x)®-1701 (Crossbond®14% cyanopropylphenyl/86% dimethyl polysiloxane) from Restek Corporation(Bellefonte, Pa.). Porous layer open tubular (PLOT) capillary columnsmay also be useful in the present invention. Such PLOT capillary GCcolumns include, but are not limited to, the CP-PoraPLOT® Q (100%styrene divinylbenzene) column from Varian Chrompack (Middelburg, TheNetherlands).

Temperature and pressure conditions for the GC analysis will varydepending upon the refrigeration/heating fluid and the tracer being usedin the composition. Cryogenic temperatures (sub-ambient, requiringliquid nitrogen, dry ice or liquid carbon dioxide) may be used in orderto provide separation of low boiling components (eitherrefrigeration/heating fluid or tracer compound(s)), when necessary.

Tracer compounds or blends may be present in concentrations that aredetectable by whichever analytical method is chosen. Additionally, thetracer concentration must be chosen such that the quantity of tracer ortracer blend does not interfere with the performance of therefrigeration/heating fluid. The tracer compound or tracer blend may bepresent at a total concentration of about 50 parts per million by weight(ppm) to about 1000 ppm. Preferably, the tracer compound or tracer blendis present at a total concentration of about 50 ppm to about 500 ppm andmost preferably, the tracer compound or tracer blend is present at atotal concentration of about 100 ppm to about 300 ppm.

The present invention further relates to a method of using the presentinventive tracer-containing refrigerant compositions, said methodcomprising combining said tracer compound with saidrefrigeration/heating fluid to make a tracer-containing refrigerantcomposition, and detecting the presence of said tracer compound in saidtracer-containing refrigerant composition. The present method is usefulto (i) determine the occurrence of dilution, adulteration orcontamination or (ii) verify the source of the refrigerant compositionof said composition.

The present invention further relates to a method of using the presentinventive tracer-containing refrigerant composition, said methodcomprising: (i) producing refrigeration by evaporating thetracer-containing refrigerant composition in the vicinity of a body tobe cooled and thereafter condensing said composition; or (ii) producingheat by condensing the tracer-containing refrigerant composition in thevicinity of the body to be heated and thereafter evaporating saidcomposition.

Vapor-compression refrigeration systems include an evaporator, acompressor, a condenser, a liquid storage receiver and an expansiondevice. A vapor-compression cycle re-uses refrigerant in multiple stepsproducing a cooling effect in one step and a heating effect in adifferent step. The cycle can be described simply as follows. Liquidrefrigerant enters an evaporator through an expansion device, and theliquid refrigerant boils in the evaporator at a low temperature to forma gas and produce cooling. The low-pressure gas enters a compressorwhere the gas is compressed to raise its pressure and temperature. Thehigh-pressure gaseous refrigerant then enters the condenser in which therefrigerant condenses and discharges its heat to the environment. Therefrigerant returns to the expansion device through which the liquidexpands from the high-pressure level in the condenser to thelow-pressure level in the evaporator, thus repeating the cycle.

EXAMPLES

Tracer-containing refrigerant compositions of the present invention wereprepared and then analyzed using several different GC columns underdiffering conditions of analysis. The retention times for therefrigeration/heating fluid and tracer compounds were determined and aregiven for each example. It should be noted that exact retention timesdetermined on a specific gas chromatograph and with a specific GC columnwill vary slightly from retention times determined from a differentinstrument and column.

All samples were analyzed on Agilent 6890 Gas Chromatographs and thedata collected and processed by Agilent Chemstation® software, bothavailable from Agilent Technologies (Palo Alto, Calif.).

Example 1

A sample of R-22 (refrigerant HCFC-22, chlorodifluoromethane) was spikedwith 100 parts per million (ppm by weight) of PFC-C318(perfluorocyclobutane). The sample was then analyzed by GC using theconditions described below:

Column: RT_(x)®-1701 (Crossbond® 14% cyanopropylphenyl/86% dimethylpolysiloxane)

Length: 105 meters Inner diameter: 0.25 millimeters Stationary phasefilm thickness: 0.25 micrometersCarrier gas and flow rate: He, 1.0 milliliter/minuteOven temperature:

Initial temperature: −20° C. Initial hold time: 15 minutes Temperatureramp rate: 10° C./minute Final temperature: 50° C. Final hold time: 0minutes (no final hold time)Detector: Flame ionization detector (FID)

Temperature: 250° C. Hydrogen flow rate: 42 milliliter/minute Airflowrate: 450 milliliter/minuteInjection port: Split

Temperature: 150° C. Head pressure: 22 psi Sample type: vapor, manualsyringe injection Sample size: 1.0 milliliter Split ratio: 50:1

The retention times for the refrigerant, R-22, and tracer, PFC-C318, aregiven in Table 2.

TABLE 2 Compound Retention time (R_(t), minutes) PFC-C318 (tracer) 11.07R-22 (refrigerant) 12.53

Example 2

A sample of R-134a (refrigerant HFC-134a, 1,1,1,2-tetrafluoroethane) wasspiked with 100 parts per million (ppm by weight) of HFC-236fa(1,1,1,3,3,3-hexafluoropropane). The sample was then analyzed by GCusing the conditions described below:

Column: RT_(x)-1® (Crossbond® 100% dimethyl polysiloxane)

Length: 105 meters Inner diameter: 0.25 millimeters Stationary phasefilm thickness: 1.0 micrometersCarrier gas and flow rate: helium, 0.75 milliliter/minuteOven temperature:

Initial temperature: −20° C. Initial hold time: 13 minutes Temperatureramp rate: 5° C./minute Final temperature: 50° C. Final hold time: 10minutesDetector: Flame ionization detector (FID)

Temperature: 250° C. Hydrogen pressure: 20 psi Air pressure: 45 psiInjection port: Split

Temperature: 175° C. Head pressure: 38 psi Sample type: vapor, manualsyringe injection Sample size: 1.0 milliliter Split ratio: 75:1

The retention times for the refrigerant, R-134a, and tracer, HFC-236fa,are given in Table 3.

TABLE 3 Compound Retention time (R_(t), minutes) R-134a (refrigerant)10.76 HFC-236fa (tracer) 12.04

Example 3

A sample of R-410A (refrigerant blend, 50 weight percent R-32,difluoromethane, and 50 weight percent R-125, pentafluoroethane) wasspiked with 100 parts per million (ppm by weight) of HFE-236fa(1-trifluoromethoxy-2,2,2-trifluoroethane). The sample was then analyzedby GC using the conditions described below:

Column: 5% Fluorcol® on Carbopack® B, 60/80 mesh

Length: 20 feet (6.1 meters) Diameter: ⅛ inch (0.32 centimeter)Carrier gas and flow rate: helium, 30 milliliter/minuteOven temperature:

Initial temperature: 60° C. Initial hold time: 3 minutes Temperatureramp rate: 8° C./minute Final temperature: 180° C. Final hold time: 10minutesDetector: flame ionization detector (FID)

Temperature: 250° C. Hydrogen pressure: 20 psi Air pressure: 45 psiInjection port: Packed

Temperature: 250° C. Head pressure: 67 psi Sample type: vapor, samplevalve injection Sample size: 50 microliter

The retention times for the refrigerant, R-410A or specifically, R-32and R-125, and tracer, HFE-236fa, are given in Table 4.

TABLE 4 Compound Retention time (R_(t), minutes) R-32 (refrigerant) 2.52R-125 (refrigerant) 3.90 HFE-236fa (tracer) 10.87

1-15. (canceled)
 16. A tracer-containing composition, said compositioncomprising a refrigeration/heating fluid and at least one tracercompound, said tracer compound being analytically detectable andselected from the group consisting of brominated compounds and iodatedcompounds, and combinations thereof with the proviso that saidrefrigeration/heating fluid is different from said tracer compound. 17.The tracer-containing composition according to claim 16, wherein saidrefrigeration/heating fluid comprises hydrofluorocarbons,hydrochlorofluorocarbons, perfluorocarbons, fluorocarbon ethers,hydrocarbons, carbon dioxide, ammonia, or mixtures thereof.
 18. Thetracer-containing composition according to claim 16, wherein saidcomposition comprises a single tracer compound.
 19. Thetracer-containing composition according to claim 16, wherein saidcomposition comprises a tracer compound or tracer blend in an amountranging from about 50 ppm to about 1000 ppm.
 20. The tracer-containingcomposition according to claim 19, wherein said composition comprises atracer compound or tracer blend in an amount ranging from about 50 ppmto about 500 ppm.
 21. The tracer-containing composition according toclaim 20, wherein said composition comprises a tracer compound or tracerblend in an amount ranging from about 100 ppm to about 300 ppm.
 22. Thetracer-containing composition according to claim 16, wherein the tracercompound is at least one compound selected from bromomethane,bromofluoromethane, bromodifluoromethane, dibromofluoromethane,tribromomethane, bromoethane, bromoethene, 1,2-dibromoethane,1-bromo-1,2-difluoroethene, iodotrifluoromethane, difluoroiodomethane,fluoroiodomethane, 1,1,2-trifluoro-1-iodoethane,1,1,2,2-tetrafluoro-1-iodoethane, 1,1,2,2-tetrafluoro-1,2-diiodoethane,iodopentafluorobenzene, and combinations thereof.
 23. Thetracer-containing composition according to claim 17, wherein saidrefrigeration/heating fluid is selected from the group consisting ofHCFC-22, HFC-23, HFC-32, HFC-41, FC-116, HCFC-124, HFC-125, HCFC-133a,HFC-134, HFC-134a, HCFC-142b, HFC-143, HFC-143a, HFC-152a, HFC-227ca,HFC-227ea, HFC-236ca, HFC-236cb, HFC-236ea, HFC-236fa, HFC-245ca,HFC-245cb, HFC-245ea, HFC-245eb, HFC-245fa, HFC-254ca, HFC-254cb,HFC-254ea, HFC-254eb, HFC-254fa, HFC-254fb, HFC-272ca, HFC-272ea,HFC-272fa, HFC-272fb, HFC-281 ea, HFC-281 fa, HFC-338 pcc, HFC-365mfc,CF₃CF₂CF₂OCHFCF₃, HFC-43-10mee, dimethyl ether, propane, propylene,cyclopropane, n-butane, isobutane, n-pentane, cyclopentane,2,2-dimethylpropane, C₄F₉OCH₃, C₄F₉OC₂H₅, perfluorobutylethylene,perfluoroethylisopropylketone, perfluoromethylisopropylketone, andmixtures thereof.
 24. The tracer containing composition according toclaim 17, wherein said refrigeration/heating fluid is selected from thegroup consisting of R-401A, R-401B, R-401C, R-402A, R-402B, R-403A,R-403B, R-404A, R-407A, R-407B, R-407C, R-408A, R-409A, R-410A, R-413A,R-414A, R-414B, R-416A, R-417A, R-419A, R-422A, R-507 and mixturesthereof.